1. Field of the Invention
This invention pertains to a personal cooling system and, more particularly, it pertains to an article of clothing to protect a person from extreme temperature and humidity conditions which may exist in a work environment.
2. Description of the Prior Art
Extreme temperature conditions are a major cause of human inability to concentrate and remain alert, and consequently are a common cause of industrial accidents and injuries. In hot environments workers are exposed to heat stress as a result of performing heavy work tasks. Heat stress may be prevented either by reducing heat flow into the body (cooling surrounding air is a customary method) or by increasing heat loss from the body. When it is impractical to cool the environment, body heat loss can be effectively increased through the utilization of a personal cooling garment.
In the past several personal cooling garments have been developed to reduce workers heat stress exposure. Such garments include circulating air systems, ice cooling devices, and circulating liquid systems. The circulating air system is a one piece impermeable suit with inner air distribution lines and a vortex tube. When connected to supplied air at 80-100 psi, cooled air flows through the suit, thus removing excess body heat. A major disadvantage is that this device requires between 15 and 25 CFM of air in order to deliver 5 CFM of cooled air to the person. This requires air compressors and therefore capital and running costs are involved. In addition, the vortex tube produces noise levels well in excess of 100 dB and, workers are tethered to the air supply via an umbilical cord which restricts mobility and the ability to pass through and work in confined spaces.
Ice cooling devices are garments containing about 50 small packets of ice which absorb the metabolic heat produced by the human body. The cooling capacity of the ice cooling garment is determined by the amount of ice contained in the garment. For practical purposes this amount is limited to 10-12 pounds of ice. Freezing and storage of the ice packets requires approximately 8 to 10 hours by utilizing a high capacity freezer located close to the changing area. Once the ice packets are removed from the freezer and placed in the garment, they begin to absorb heat. Therefore, donning the garment must be delayed to the last moment to prevent partial ice melting and therefore reduction in the cooling capacity of the garment.
Circulating liquid systems utilize a heat sink or reservoir containing water, ice, a pump generally powered by batteries, and a heat exchanger. Cool water is circulated in a closed system through tubes within the skin where it absorbs heat and then through the heat exchanger which is in contact with the heat sink. The heat sink normally worn as a back-pack may weigh 22 pounds or more, depending upon design. Its weight and size impose considerable restrictions upon the wearer, such as the size of a passageway that can be entered. In addition, facilities are required for storage and production of the heat sinks. Accordingly, consideration of the above factors results in conventional personal cooling garments being impractical or not applicable to heat stress relief of many workers.